Can the viability of a nonunion be evaluated using SPECT/CT? A preliminary retrospective study

Introduction: The importance of the vitality of a nonunion is crucial for the planning of the reconstructive procedure. Purpose of the present study is to analyze the role of single photon emission computed tomography (SPECT) in diagnosing and planning the treatment of atrophic nonunions in the upper and lower extremity. Patients and Methods: This study examined retrospectively the SPECT/CT scans of 10 patients (mean age=44.5+/-16.5 years, 9 males/1 female, 4 tibia/4 femur/1 radius/1 fibula) who underwent surgical exploration for suspected avital pseudarthrosis. Surgical and histopathological findings were compared with the radiologists' findings to assess the sensitivity and specificity of SPECT in diagnosing avital nonunions. The average interval from the osteosynthesis until their SPECT scan was 18 months. All surgical findings have been documented electronically in the hospital computer system. Results of the radiologist's reading were then compared with surgical exploration and histopathological findings and specifity and sensitivity was calculated. Results: There were 4 vital and 6 nonvital pseudarthroses. SPECT scans identified all the vital pseudarthroses and 3 of the 6 nonvital pseudarthroses. The sensitivity of SPECT in diagnosing non-vital atrophic nonunions is 50% and the specifity 100%. Conclusions: SPECT/CT scan is a test with a low sensitivity but good specificity that excludes infection and confirms nonviability of the nonunion site. However, we shall wait for larger pool of research results in order to incorporate this test in routine clinical use.